The present invention relates generally to footwear, and more particularly, to a shoe sole that has been adapted to improve a walker""s power, posture, and comfort. This is accomplished by a unique sole arrangement, which optimizes shoe cushioning and spring or rebound. Although the shoe provides benefits which extend to all forms of footwear, it has proven especially effective for use by people who walk for exercise and/or competition, and is described in the context of race walking below.
In recent years, there has been an explosion in the physical fitness industry, and correspondingly, in the desire for equipment which improves an individual""s performance of activities which promote good health. One area which has experienced particular growth involves low-impact cardiovascular exercise, an endeavor known to improve physical condition without unduly taxing an individual""s joints. Activities such as walking have thus popularized, and have developed into competition sports such as performance walking or race walking. The sport serves as an increasingly popular form of exercise and recreation, attracting persons of differing levels of skill and physical ability. The fitness industry, however, has been slow in recognizing this trend, and has yet to develop an acceptable walking shoe. Walkers have thus been forced to make do with running shoes, shoes designed to accommodate a high impact activity which requires very different foot posture, stride technique, impact absorption, and overall shoe use from that of performance walking or race walking.
Walking technique consists of a series of steps, where each step constitutes a cycle in which the walker shifts from a single support phase, to a double support phase, and then back to the single support phase. In the single support phase, the walker""s entire weight is balanced on one foot, the other foot being moved forward so as to move the walker into the double support phase. In the double support phase, the walker""s weight is balanced between a leading and a trailing foot. The trailing foot is used to push the walker forward so as to again enter the single support phase, and begin the cycle anew. The aforementioned xe2x80x9cpush-offxe2x80x9d begins during the single support phase when the walker""s center of gravity passes over the supporting foot. The walker, at all times, has at least one foot in contact with the ground, reducing the impact associated with each step, and resulting in an overall lower impact exercise routine.
With each step in the stride phase, the athlete""s forward foot lands on the heel (xe2x80x9cheel strikexe2x80x9d), and moves forward to a planted position with the heel and ball of the foot supported from below. The ball of the foot acts as a fulcrum, the walker""s foot pivoting forward about the fulcrum as the walker""s center of gravity passes thereover. This accommodates push-off by the walker""s toes. The walker does not push-off with the trailing foot until the leading foot is planted so as to provide the walker with stable support. A slight forward lean of approximately 5 degrees from vertical provides the walker with an ideal walking posture and helps with forward momentum. Such lean should be from the ankles, rather than from the waist because a forward bend from the waist shortens the walker""s stride and compromises breathing power by cramping the person""s lungs.
In conventional shoes, the wearer""s heel is elevated relative to the toes and the ball of the foot when the foot is planted. This arrangement leads to improper walking posture, which can lead to injury, and detracts from the wearer""s walking power and walking speed. Because of the forwardly declining orientation of the wearer""s foot, the wearer will tend to stand with a body reclined slightly so as to maintain balance. This results in an unhealthy posture and increases the likelihood of injury to the walker""s lower torso. Conventional shoes also detract from walking efficiency because it is necessary to provide a sole with an undersurface which is generally planar from the shoe""s heel to the tip of its toe. Such a planar surface is made necessary in order to provide a walker adequate balance while providing a motive force and bending the forepart of the shoe. However, during fast walking, planar shoes may be uncomfortable and may place stress on the Achilles tendon.
According to one aspect of the present invention, a walking shoe includes a segmented midsole with a thickness that changes from back to front. The midsole includes a back portion and an arcuate front portion. The arcuate front portion interfaces with the back portion and includes a plurality of forward sections. At least one of the forward sections differs in density relative to another of the forward sections. Relatively denser forward sections facilitate a rebound or spring effect as a walker pushes off during a walking stride. Relatively less dense forward sections add cushioning, making the walking stride more comfortable by lessening impact to the walker""s foot.